Devices and methods for bone fixation

ABSTRACT

Devices and methods for bone fixation including a bone fixation system including a bone plate or intervertebral spacer including a plurality of apertures dimensioned to receive bone fasteners and at least one polymeric element capable of transitioning from a solid state to a flowable state. The polymeric element transitions to a flowable state as a result of exposure to ultrasonic vibration. The polymeric element is placed on the bone plate or intervertebral spacer adjacent a fastener in an aperture and acts to prevent rotational and/or translational movement of the fastener relative to the bone plate or intervertebral spacer.

CROSS REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates generally to fastener anti-backout mechanisms forbone fixation devices.

Description of the Related Art

In the orthopedic medical device industry, bone screws are commonly usedto secure various medical devices in position with respect to apatient's skeletal structure. Bone screw back-out, both rotationalback-out and translational back-out, is a problem of particular concernin the medical device industry. As such, there is a need for improvedanti-backout solutions for use with bone fixation devices.

Ultrasonic welding is an industrial technique whereby high-frequencyultrasonic acoustic vibrations are applied to workpieces being heldtogether under pressure to create a solid-state weld. Thesehigh-frequency ultrasonic acoustic vibrations are generally provided bydevices known to those skilled in the art as sonotrodes. Sonotrodes arecommonly used in various arts to liquefy polymeric materials toultrasonically weld materials together.

SUMMARY OF THE INVENTION

This disclosure concerns devices and methods for providing ananti-backout component to bone fixation devices comprising at least onebone fastener. Specifically, the disclosure is directed to in-situultrasonic welding solutions for bone fixations, to solve at least someof the problems existing in the prior art. The anti-backout componentdescribed below is contemplated for use in any application in orthopedicor spine surgery when movement of one or more components of an implantis desired at the time of implantation, and then prevention of movementof any of those same components relative to each other is desired afterthe implant has been implanted.

A first exemplary method for bone fixation is provided including thesteps: positioning a plate adjacent to a patient's bone, the plateincluding an aperture dimensioned to receive a fastener there throughand a polymeric element adjacent the aperture; inserting a fastenerthrough the aperture; applying a sonotrode to the polymeric elementuntil the polymeric element reaches a flowable state; allowing thepolymeric element to flow into a space in the aperture that is adjacentthe fastener, such that the polymeric element is in contact with boththe plate and the fastener; allowing the polymeric element to harden toa solid state such that the polymeric element prevents the fastener frommoving relative to the plate.

A second exemplary method for bone fixation, includes the steps of:positioning a spacer in an intervertebral disc space between a firstvertebral body and a second vertebral body, the spacer including a wallhaving an aperture dimensioned for receiving a fastener therein and apolymeric element adjacent the aperture; inserting a fastener throughthe aperture and into one of the first and second vertebral bodies;applying a sonotrode to the polymeric element until the polymericelement reaches a flowable state; allowing the polymeric element to flowinto a space adjacent the fastener in the aperture such that thepolymeric element is in contact with both the wall of the spacer and thefastener; allowing the polymeric element to harden to a solid state,thereby preventing the fastener from moving relative to the wall of thespacer.

A first exemplary embodiment of a bone fixation system is provided, thebone fixation system including: a bone fixation having an aperturedimensioned to receive a fastener there through and a polymeric elementadjacent the aperture; a fastener configured to secure the implant to apatient's bone; and a sonotrode.

A second embodiment of a bone fixation system is provided, the bonefixation system including: a spacer configured for placement within anintervertebral disc space of a patient between a first vertebral bodyand a second vertebral body, the spacer further including: a wall havingat least one aperture dimensioned for receiving a fastener there throughand at least one polymeric element disposed adjacent to each aperture;at least one fastener configured to extend through one of the one ormore apertures to secure the spacer to one of the first and secondvertebral bodies; a sonotrode configured change a physical state of thepolymeric element; wherein upon introducing the sonotrode to thepolymeric element, material of the polymeric element flows into a spaceadjacent the fastener in the aperture such that the material of thepolymeric element is in contact with both the wall of the spacer and thefastener; and wherein upon removing the sonotrode from the polymericelement, the material of the polymeric element is configured to hardento a solid state, thereby preventing the fastener from moving relativeto the wall of the spacer. A first embodiment of a method for bonefixation, includes the steps of: positioning a plate adjacent to apatient's bone, the plate including an aperture dimensioned to receive afastener there through and a polymeric element adjacent the aperture;inserting a fastener through the aperture; applying a sonotrode to thepolymeric element until the polymeric element reaches a flowable state;allowing the polymeric element to flow into a space in the aperture thatis adjacent the fastener, such that the polymeric element is in contactwith both the plate and the fastener; allowing the polymeric element toharden to a solid state such that the polymeric element prevents thefastener from moving relative to the plate.

In some embodiments, the plate includes a recess in a surface of theplate, wherein the recess is in communication with at least a portion ofthe at least one aperture.

In some embodiments, the polymeric element may be installed in therecess prior to positioning the plate adjacent to a patient's bone, orsubsequent to positioning the plate adjacent to the patient's bone.

In some embodiments, the plate comes preassembled with the polymericelement installed in the recess.

In some embodiments, the recess may be in communication with the atleast one aperture along at least a portion of the perimeter of theaperture. In some embodiments the recess may be in communication withthe at least one aperture along the entire perimeter of the aperture.

In some embodiments, the polymeric element may be made out of athermoplastic material. The thermoplastic material may liquefy when incontact with a sonotrode. Once liquefied the polymeric material may flowfor e.g. into the recess on the circumferential surface of the head ofthe fastener.

In some embodiments, the polymeric element and/or material may preventthe fastener from translating in a direction opposite of the directionof insertion. In some embodiments the polymeric element and/or materialmay prevent the fastener from rotating.

In some embodiments, the fastener may include a shank portion and a headportion having a circumferential surface, wherein the circumferentialsurface of the head comprises a recess. After the fastener is insertedthrough the plate, and a sonotrode is introduced to liquefy thepolymeric element, the polymeric element may flow into the recess of thehead of the fastener, to help secure the fastener with respect to theplate.

In some embodiments, the plate may be configured for fixation on anyregion of a patient's skeletal system including for example: spinalfixation or long bone fixation.

The plate may include one or more apertures, each aperture dimensionedto receive a fastener there through. One or more fasteners may beinserted through each of the respective apertures. The plate may includea recess in a surface of the plate that is adjacent to and incommunication with at one or more apertures. The recess in the surfaceof the plate may be adjacent to and in communication with each of aplurality of apertures.

In some embodiments, the plate may include a recess in a surface of theplate that is adjacent to and in communication with at least twoapertures. In such embodiments, the polymeric material to may be allowedto flow in the at least two apertures.

In some embodiments, the recess in the surface of the plate may beadjacent to and in communication with each of a plurality of apertures.In such embodiments, the polymeric material may be allowed to flow ineach of the plurality of apertures.

A second embodiment of a method for bone fixation is provided, includingthe steps of: positioning a spacer in an intervertebral disc spacebetween a first vertebral body and a second vertebral body, the spacerincluding a wall having an aperture dimensioned for receiving a fastenerthere through, and a polymeric element adjacent the aperture; insertinga fastener through the aperture and into one of the first and secondvertebral bodies; applying a sonotrode to the polymeric element untilthe polymeric element reaches a flowable state; allowing the polymericelement to flow into a space adjacent the fastener in the aperture suchthat the polymeric element is in contact with both the wall of thespacer and the fastener; allowing the polymeric element to harden to asolid state, thereby preventing the fastener from moving relative to thewall of the spacer.

In some embodiments, the spacer is a unitary piece. In some embodiments,the spacer may include a modular spacer with a body that is detachablefrom a wall. The body may inserted into the intervertebral disc spaceseparately from the wall.

In some embodiments, the body may be generally U-shaped. The wall maycomposed of a material different than the body of the spacer. One ormore of the wall and the body may include one or more apertures, eachaperture dimensioned to receive a fastener therein. One or more of thewall and the body may include a recess in a surface of the wall, whereinthe recess is in communication with the aperture.

In some embodiments, the step of inserting a fastener through theaperture may include inserting a plurality of fasteners throughrespective apertures.

In some embodiments, the polymeric element may be installed in therecess prior to the step of positioning the spacer into theintervertebral disc space. The polymeric element may be made from athermoplastic material. The polymeric element may prevent the fastenerfrom translating in a direction opposite of the direction of insertion.The polymeric element may also prevent the fastener from rotating.

In some embodiment, the recess may be in communication with the at leastone aperture along at least a portion of the perimeter of the aperture.The recess may be in communication with the at least one aperture alongthe entire perimeter of the aperture.

In some embodiments, the fastener may include a shank portion and a headportion having a circumferential surface, wherein the circumferentialsurface of the head comprises a recess.

In some embodiments, after applying a sonotrode to the polymeric elementuntil the polymeric element reaches a flowable state the polymericmaterial may be allowed to flow into the recess on the circumferentialsurface of the head of the fastener while in the flowable state.

In some embodiments, the wall may include a recess in a surface of thewall that is adjacent to and in communication with at least twoapertures.

A first embodiment of a bone fixation system is provided, the bonefixation system including: a bone fixation having an aperturedimensioned to receive a fastener there through and a polymeric elementadjacent the aperture; a fastener configured to secure the implant to apatient's bone; and a sonotrode.

In some embodiments, the bone fixation may be for e.g. a fixation plate,a spacer, an expandable spacer, a distraction rod, an intramedullarynail, or any other bone fixation. In some embodiments, the bone fixationmay be configured for spinal fixation, in other embodiments the bonefixation may be configured long bone fixation. As one with skill in theart may appreciate, the implant may be configured for use in any medicalprocedure requiring an implant.

In some embodiments, the bone fixation may include a plurality ofapertures dimensioned to receive a fastener there through. The systemmay further include a plurality of fasteners.

In some embodiments the implant may be a fixation plate having a recessin a surface of the plate, wherein the recess is in communication withthe aperture. The polymeric element may be installed in the recess priorto the step of positioning the fixation plate adjacent to a patient'sbone.

In some embodiments, the recess may be in communication with the atleast one aperture along at least a portion of the perimeter of theaperture. The recess may be in communication with the at least oneaperture along the entire perimeter of the aperture.

In some embodiments the polymeric element is made out of a thermoplasticmaterial. The polymeric element may prevent the fastener fromtranslating in a direction opposite of the direction of insertion. Insome embodiments the polymeric element may prevent the fastener fromrotating.

In some embodiments, the fastener may include a shank portion and a headportion having a circumferential surface, wherein the circumferentialsurface of the head comprises a recess. The polymeric material may beallowed to flow into the recess on the circumferential surface of thehead of the fastener while in a flowable state.

In some embodiments where the bone fixation is an intervertebral spacer,the spacer may be a single, unitary piece. In some embodiments anaperture may be located on a wall of the spacer. The wall may be ananterior wall of the intervertebral spacer. The wall may be detachablefrom the body of the intervertebral spacer. The body may be generallyU-shaped.

A second embodiment of a bone fixation system is provided, the bonefixation system including: a spacer configured for placement within anintervertebral disc space of a patient between a first vertebral bodyand a second vertebral body, the spacer further including: a wall havingat least one aperture dimensioned for receiving a fastener there throughand at least one polymeric element disposed adjacent to each aperture;at least one fastener configured to extend through one of the one ormore apertures to secure the spacer to one of the first and secondvertebral bodies; a sonotrode configured change a physical state of thepolymeric element; wherein upon introducing the sonotrode to thepolymeric element, material of the polymeric element flows into a spaceadjacent the fastener in the aperture such that the material of thepolymeric element is in contact with both the wall of the spacer and thefastener; and wherein upon removing the sonotrode from the polymericelement, the material of the polymeric element is configured to hardento a solid state, thereby preventing the fastener from moving relativeto the wall of the spacer.

In some embodiments, the spacer may be a unitary piece. The spacer mayhave a body that is detachable from the wall. The body may be configuredto be inserted into the intervertebral disc space separately from thewall. The body may be generally U-shaped. The wall may be made out of adifferent material than the body of the spacer. The wall may have aplurality of apertures, each dimensioned to receive a fastener therein.

The bone fixation system may include a plurality of fasteners configuredto extend through a respective plurality of apertures.

In some embodiments, the polymeric element may be installed in therecess prior to the positioning the spacer into the intervertebral discspace. The polymeric element may be made out of a thermoplasticmaterial. The polymeric element may prevent the fastener fromtranslating in a direction opposite of the direction of insertion. Thepolymeric element may also prevent the fastener from rotating.

The fasteners may include a shank portion and a head portion having acircumferential surface, wherein the circumferential surface of the headcomprises a recess. The polymeric material may be allowed to flow intothe recess on the circumferential surface of the head of the fastenerwhile in the flowable state.

In some embodiments the wall may a recess in a surface of the wall thatis adjacent to and in communication with at least two apertures. Thepolymeric material may be allowed to flow into the at least twoapertures. The recess may be in the surface of the wall adjacent to andin communication with each of the plurality of apertures.

These and other features and benefits are further described in thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a bone fixation system in accordancewith a first embodiment;

FIG. 2 shows a perspective view of the bone fixation system of FIG. 1;

FIG. 3 shows a perspective view of a polymeric element of the bonefixation system of FIG. 1;

FIG. 4 shows a cross-sectional side view of the bone fixation system ofFIG. 1;

FIG. 5 shows perspective view of a bone fixation implant system inaccordance with a second embodiment;

FIG. 6 shows side view of the bone fixation system of FIG. 5;

FIG. 7 shows a perspective view of the interbody spacer component of thebone fixation system of FIG. 5;

FIG. 8 shows a front view of the intervertebral spacer of the bonefixation system of FIG. 5;

FIG. 9 shows a polymeric element in accordance with a second embodiment;

FIG. 10 shows an embodiment of a fastener of the bone fixation system ofFIG. 5;

FIG. 11 shows a perspective view of a bone fixation system in accordancewith a third embodiment;

FIG. 12 shows an exploded perspective view of the bone fixation systemof FIG. 11;

FIG. 13 shows a view top of the bone fixation system of FIG. 11; and

FIG. 14 shows a diagram of an exemplary sonotrode system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of explanation and not limitation, details and descriptionsof certain preferred embodiments are hereinafter provided such that onehaving ordinary skill in the art may be enabled to make and use theinvention. These details and descriptions are representative only ofcertain preferred embodiments, however a myriad of other embodimentswhich will not be expressly described will be readily understood bythose having skill in the art upon a thorough review hereof.Accordingly, any reviewer of the instant disclosure should interpret thescope of the invention by the claims, and such scope shall not belimited by the embodiments described and illustrated herein.

As one with skill in the art may appreciate, the bone fixation system 10may include any device intended to be placed adjacent a bone within thehuman body including: plates and interbody spacers. The bone fixationsystem may be constructed out of any suitable biocompatible materialsincluding, for example, autograft, allograft, titanium, cobalt chrome,carbon fiber, PEEK, PEK, PEKK or a combination thereof, or any othermaterial known in the field of bone fixation technology.

FIGS. 1-4 illustrate an exemplary embodiment of a bone fixation systemincluding a bone plate 12, a plurality of fasteners 16 and a polymericelement 14. According this exemplary embodiment, the bone plate 12includes a plurality of apertures 17 each dimensioned to receive afastener 16 there through. The bone plate 12 further includes a recess18 adjacent each aperture 17, the recess 18 being configured to housethe polymeric element 14. As shown in this embodiment, each recess 18corresponds to a single aperture 17. However, plate configurations arealso contemplated wherein a single recess is in communication with two,three, four or more apertures.

According to one aspect, the fastener 16 may include any device intendedto secure an implant with respect to a bone structure of a patient. Byway of example only a fastener may include, but is not limited to, abone anchor, a bone screw, a spike, a staple or a blade. As illustratedin the exemplary embodiment in FIG. 4, the fastener 16 is a bone screwthat includes a head and a threaded shank.

According to another aspect, the polymeric element is at least partiallycomprised of a thermoplastic material. According to the exemplaryembodiment, the thermoplastic material that can transition from agenerally solid state (e.g. not flowable) flowable state when thethermoplastic material is heated. In particular, the thermoplasticmaterial transitions from a solid state at room temperature to aflowable state upon application of ultrasonic vibration to the polymericelement. According to the exemplary embodiment, the bone fixation system10 pre-assembled prior to use in surgery such that the polymeric element14 is housed within the recess 18 of the plate 12. The polymeric element14 may be dimensioned to correspond to the shape of the recess 17 in thebone plate 12 to which the polymeric element 14 is applied. According tothis embodiment, the polymeric element 14 has an annular shape thatcorresponds generally to the shape of the aperture 17 and has an innerdiameter 14 a that is dimensioned to allow passage of the fastenerthrough the center of the polymeric element. FIG. 3 shows a perspectiveview of a polymeric element 14 having an inner diameter 14 a dimensionedto receive a fastener 16. The size of the inner diameter 14 a may bechosen depending on the type and size of fastener 16 used. However,preassembly of the plate 12 and polymeric element 14 is not required,and the polymeric element(s) 14 may be provided separately to beassembled, for example, during surgery.

In some embodiments, a keyed portion 13 or any portion of the polymericelement 14, remain accessible even with a fastener 16 inserted through acorresponding aperture 17. This accessible portion 24 of the polymericelement is sized to allow sufficient contact with the distal tip 45 of asonotrode 40, in order to apply ultrasonic vibrations to the polymericelement thereby causing the thermoplastic component(s) to become heatedand consequently transition to a flowable state.

In some embodiments, the plate 12 may include a correspondinganti-rotation groove 13, (see FIG. 2) such that when the polymericelement 14 is placed adjacent to the aperture 17, the anti-rotationfeature 15 of the polymeric element 14 will complementarily fit withinthe anti-rotation feature 13 of the plate 12. This interaction mayprevent the polymeric element 14 from rotating when a fastener 16 isinserted through the apertures 17.

During use, a bone plate is implanted adjacent a patient's bone.According to the exemplary embodiment, the polymeric element ispre-installed in the recess in the bone plate prior to implantation in apatient. Upon placement of the bone plate adjacent the patient's bone,at least one fastener is inserted through an aperture and into thepatient's bone to secure the bone plate to the bone. After placement ofthe one or more fasteners, the plate may be secured with respect to thebone of a patient, and the surgeon can ultrasonically weld the fastenersto the plate. In doing so, the surgeon may for example, introduce thedistal tip of a sonotrode to the thermoplastic element. Application ofultrasonic vibration from the sonotrode to the polymeric element causesthe thermoplastic component(s) to heat up and consequently becomeflowable. The flowable thermoplastic material is then allowed to flowinto the aperture and infiltrate the space in and/or around the proximalend of the fastener within the aperture. The polymeric element is thenallowed to cool and return to a solid state, thereby preventing thefastener from rotating and/or translating in the aperture of the plate.According to one aspect, once the polymeric element has infiltrated thespace in and/or around the proximal end of the fastener, it is activelycooled to a solid state. According to another aspect, thermoplasticmaterial may flow into grooves on the fastener, or over the heads of thefasteners. Additionally, thermoplastic material may flow within thekeyed groove of the plate. In an alternative method, the polymericelement is provided separately from the bone plate, and is applied tothe bone plate after the steps of applying the bone plate to thepatient's bone and inserting the fasteners through the apertures in thebone plate.

FIG. 4 shows a cross-sectional side view of a bone fixation system 10 inaccordance with the first embodiment, the bone fixation system 10 shownincluding at least one fastener 16 inserted there through, with aportion of a polymeric element 14 disposed between the fastener 16 andthe plate 12. The polymeric element 14 is shown securing the bonefixation device 16 relative to the plate 12.

FIGS. 5-10 illustrate an alternative exemplary embodiment, having manyof the same features as the embodiment described above and shown inFIGS. 1-4. FIG. 5 shows perspective view of a bone fixation system 20 inaccordance with a second embodiment, the bone fixation system 20 shownincluding an intervertebral spacer 22 having a wall 21 that includes atleast one aperture 27 there through. According to the exemplaryembodiment shown in FIG. 5, the spacer 22 has an anterior wall 21 with aplurality of apertures 27 dimensioned to receive bone fasteners 36. Eachof the apertures 27 has a corresponding recess 28 dimensioned to housethe polymeric element 24. It is also contemplated that wall 21 of thespacer 22 can include fewer recesses than apertures, wherein a singlerecess is in communication with more than one aperture.

According to this exemplary embodiment, FIG. 7 shows a perspective viewof the spacer having a one or more apertures disposed on an anteriorwall 21 thereof. The spacer 22 is shown having a top surface, a bottomsurface, and one or more walls forming a fusion aperture. The topsurface is shown including anti-migration features to engage theendplates of the vertebral bodies adjacent the intervertebral space intowhich the spacer is inserted. The fusion aperture is configured toreceive bone graft, or bone graft substitute material therein, topromote fusion across the disc space.

In some embodiments, the polymeric element 24 may come preinstalledadjacent to the aperture 27 of the spacer 22. In other embodiments, thepolymeric element may come preinstalled adjacent to the fastener 26. Instill some other embodiments, the polymeric element 24 may be providedseparately from the intervertebral spacer and positioned as need tosecure to secure the fastener(s) 26 with respect to the spacer 22 duringsurgery.

In some embodiments, at least a portion of the polymeric element 24remains exposed after a fastener 26 is inserted through an aperture 27of the spacer 22. As described in the previous embodiment, the distaltip of a sonotrode is applied to the exposed portion of the polymericelement to transmit ultrasonic vibrations to the polymeric element,causing it to heat up and transition to a flowable state. Additionally,an exposed portion of the polymeric element 24 may be achieved for e.g.:by creating a channel in the spacer 22, creating a channel in thefastener 26, or including an anti-rotation feature on the polymericelement 24, similar to the anti-rotation feature of the firstembodiment.

During use, the bone fixation device according to the embodimentillustrated in FIGS. 5-10 is installed in a similar method.Specifically, the polymeric element(s) are pre-installed in recesses inthe aperture(s) of the spacer and the spacer is introduced into theintervertebral space of a patient. Upon desired placement of the spacer,at least one fastener is inserted into an aperture in the spacer. Afterinsertion of the fastener, the distal tip of a sonotrode is applied tothe polymeric element to transmit ultrasonic vibrations to the polymericelement, causing the polymeric element to heat up and transition to aflowable state. The flowable polymeric element is allowed to flow intothe space in the aperture adjacent to the proximal end of the fastener,and allowed to cool to a solid state. Once in a solid state, thepolymeric element prevents rotation and/or translation of the fastenerwith respect to the spacer. According to an alternative method, thepolymeric element is provided separately from the spacer, and is appliedto the aperture of the spacer after the fastener has been inserted.

FIGS. 11-13 illustrate a bone fixation system 30 in accordance with athird embodiment, the bone fixation system 30 is used in the same wayand includes substantially the same features as shown in the exemplaryembodiment of FIGS. 5-10, but further including a modular intervertebralspacer including a body 32, and a detachable wall 33, the detachablewall 33 including a plurality of apertures dimensioned to receive aplurality of fasteners 37 configured to secure the modularintervertebral spacer in an intervertebral space of a patient Thedetachable wall 33 includes a plurality of recesses 38, each recess 38adjacent to and in communication with two apertures 37. Each recess 38is configured to house a polymeric element 34 therein.

In some embodiments, the modular intervertebral spacer system 32, 33 mayinclude any spacer system having two or more parts, wherein two or moreof the parts are joined together to form a unitary spacer body. In use,the modular intervertebral spacer may be pre-assembled prior toinsertion, or the body 32 and the detachable wall 33 may be insertedseparately. The body and detachable may be comprised of the samematerial or different materials. By way of example only, the body 32 maybe constructed of a plastic material and the detachable wall 33 may beconstructed of titanium or other suitable medical grade metal, or viceversa.

FIG. 14 shows a diagram of an exemplary sonotrode 40 configured to applyultrasonic vibrations to cause the polymeric element to transition froma solid state to a flowable state. The ultrasonic vibrations may becreated by a series of components, for example: a power supply, aconverter, a booster, and a horn.

The power supply may receive an electrical line voltage and convert itto an operating frequency (e.g. 20 kHz). This electrical energy may besent through a radio-frequency cable to a converter. The converter mayuse piezoelectric ceramics to convert the electrical energy tomechanical vibrations at an operating frequency of the power supply.This mechanical vibration may be increased or decreased depending on theconfiguration of the booster and horn. Depending on the polymericmaterials used in the parts.

In operation, mechanical vibrations may be delivered to the parts to bewelded. The parts also may be put under a mechanical load. Under thisload, the mechanical vibrations may be transmitted to the interfacebetween the material surfaces, which focuses the vibration to createintermolecular and surface friction. This friction creates heat and asubsequent transition from solid to liquid. The solid may then solidifyinto a welded bond.

Now, although particular features and embodiments have been described inan effort to enable those with skill in the art to make and use theclaimed invention, it should be understood that several variations,alterations or substitutions can be achieved to arrive at a containerwith integrated dome applicator and hinged cap. Nothing in thisdescription shall be construed as limiting the spirit and scope of theinvention as set forth in the appended claims, below.

What is claimed is:
 1. A method for bone fixation, comprising the stepsof: positioning a spacer in an intervertebral disc space between a firstvertebral body and a second vertebral body, the spacer including a wallhaving an aperture dimensioned for receiving a fastener there throughand a polymeric element adjacent the aperture; inserting a fastenerthrough the aperture and into one of the first and second vertebralbodies; applying a sonotrode to the polymeric element until thepolymeric element reaches a flowable state; allowing the polymericelement to flow into a space adjacent the fastener in the aperture suchthat the polymeric element is in contact with both the wall of thespacer and the fastener; allowing the polymeric element to harden to asolid state, thereby preventing the fastener from moving relative to thewall of the spacer.
 2. The method of claim 1, wherein the spacer is aunitary piece.
 3. The method of claim 1, wherein the spacer includes abody that is detachable from the wall.
 4. The method of claim 3, whereinthe body is inserted into the intervertebral disc space separately fromthe wall.
 5. The method of claim 3, wherein the body is generallyU-shaped.
 6. The method of claim 3, wherein the wall comprises adifferent material than the body of the spacer.
 7. The method of claim1, wherein the wall includes a plurality of apertures, each dimensionedto receive a fastener therein.
 8. The method of claim 7, wherein thestep of inserting the fastener through the aperture includes inserting aplurality of fasteners through respective apertures.
 9. The method ofclaim 7, wherein the wall includes a recess in a surface of the wallthat is adjacent to and in communication with at least two of theplurality of apertures.
 10. The method of claim 9, further comprisingallowing the polymeric material to flow in the at least two apertures.11. The method of claim 7, wherein a recess in a surface of the wall isadjacent to and in communication with each of the plurality ofapertures.
 12. The method of claim 11, further comprising allowing thepolymeric material to flow in each of the plurality of apertures. 13.The method of claim 1, wherein the wall includes a recess in a surfaceof the wall, wherein the recess is in communication with the aperture.14. The method of claim 13, wherein the polymeric element is installedin the recess prior to the step of positioning the spacer into theintervertebral disc space.
 15. The method of claim 13, wherein therecess is in communication with the aperture along at least a portion ofa perimeter of the aperture.
 16. The method of claim 15, wherein therecess is in communication with the aperture along an entirety of theperimeter of the aperture.
 17. The method of claim 1, wherein thepolymeric element comprises a thermoplastic material.
 18. The method ofclaim 1, wherein the polymeric element prevents the fastener fromtranslating in a direction opposite of a direction of insertion of thefastener.
 19. The method of claim 1, wherein the polymeric elementprevents the fastener from rotating.
 20. The method of claim 1, whereinthe fastener comprises: a shank portion and a head portion having acircumferential surface, wherein the circumferential surface of the headcomprises a recess, and wherein the polymeric material is allowed toflow into the recess on the circumferential surface of the head of thefastener while in the flowable state.